Previously, as a multiple addressing facsimile system which used radio circuits, there was, for example, one which was recorded in Oki Denki Kenkyu Kaihatsu 137, Vol. 55 No. 1 (1 Jan. 1988) Pages 23-26, "Facsimile for Disaster Prevention Radio Communications System" by Gotoh, Hagiya, and Shimizu. This multiple addressing facsimile system was one which used ground wave radio circuits such as microwave circuits and quasi-milliwave circuits. This system comprised control stations installed in the respective regions, branch stations installed in each district inside the regions of these control stations, multiple terminal stations inside the respective districts, and relay stations which conducted the radio circuit relays between the branch stations and the control stations. In this system, a facsimile device for issuing commands was provided in the control stations, and a facsimile device for issuing commands and a facsimile for receiving commands were provided in each of the respective branch stations. Each of the respective terminal stations was provided with a facsimile device for receiving commands.
According to this multiple addressing facsimile system, it was possible to execute, by using the command facsimile device of the control station, a simultaneous command communication which simultaneously transmits a facsimile signal to all of the branch station facsimile devices and all of the terminal station facsimile devices, and the branch simultaneous command communications for the facsimile signals having, as their objective, all of the terminal stations of the respective branch stations, and the like.
However, in this type of a multiple addressing facsimile system, there were the following kinds of problems.
(a) In the case of transmitting a facsimile signal from the command facsimile device of the control station to the command receiving facsimile device of the respective terminal stations by using a radio circuit, the signal had to be transmitted to the respective terminal stations via the relay stations and the branch stations. As was mentioned above, at the branch stations, there was a necessity for a facsimile device used for issuing commands and receiving commands, and a device for the purpose of transmitting and receiving that facsimile signal by a radio circuit became necessary. Also, as for the relay stations, since there was a requirement for at least one or more stations within an line of sight communications distance in order to relay, for example, between the control station and the branch stations, in the prior multiple addressing facsimile system, there were the problems that the construction of the entire system became complicated due to relaying these, and that it was not economical. PA1 (b) In the above mentioned multiple addressing facsimile system, there was the problem that when a facsimile signal was transmitted to multiple terminal stations using the radio circuits, it could not be operated in the mode wherein optional terminal stations were freely combined, since the system was a multiple group addressing system wherein the terminal stations were combined into a group unit, for example, a district unit. PA1 (1) The audio channel of the AV service consists of a monaural broadcast, for example, and service is provided by allocating channel ch1 to audio use, and channel ch2 to facsimile broadcast use. PA1 (2) Besides audio channels ch1, ch2, for example, a channel ch3 is additionally provided, and service is provided by allocating channels ch1, ch2 to audio use, and channel ch3 to facsimile broadcast use.
Thus, the inventors of the present invention in this application, as a result of studying the case of the above mentioned (a), eliminated the branch stations and the relay stations by using existing satellite communications systems, and thought of conducting facsimile multiple address communications from the control station directly to the terminal stations.
However, in the existing audio visual (hereinafter written as AV) service which uses communications satellites, 2 channels are used as audio circuits which are used as a stereo or monaural broadcast circuit in response to the contents of the service. During stereo broadcasting, the left voice is transmitted on channel 1 (ch1), the right voice is transmitted on channel 2 (ch2), and during monaural broadcasts, the same voice signal is transmitted on both ch1 and ch2.
In this case, the communications satellite receiving device has a satellite receiving antenna, and a tuner used for satellite reception, an AV decoder, and an image receiver are connected to this antenna. With these kinds of devices, the satellite electromagnetic waves that are received from the satellite receiving antenna can be detected at the tuner used for satellite reception. This detected output is demodulated by the AV decoder into a video signal (image signal) using one channel and an audio signal using two channels (channel ch1, ch2), which are supplied to an AV monitor.
If an attempt is to be made to realize the above mentioned type of facsimile multiple addressing or facsimile broadcasting by using the AV service of this type of satellite communications circuit, the following two methods can be considered.
However, in the case of configuring a facsimile reception system by using the above mentioned method (1), because the audio channel becomes a monaural system, the broadcast of stereo programs becomes impossible, and the quality of the AV service becomes extremely degraded. Also, in the case of configuring a facsimile reception system by using the above mentioned method (2), because service is provided by allocating channel ch3 to facsimile broadcast use on the transmitting side, the audio channel must be newly enlarged and installed in the communications satellite receiving device of the receiving side, and this places a big load on the receiving side. Therefore, even if facsimile multiple address service or facsimile broadcast service was provided by using the prior technology, it was difficult to offer a facsimile reception system that was sufficiently satisfactory, technologically as well as economically.